1. Field of Invention
The background of this invention relates to systems for controlling animal access and, more particularly, for systems providing pet controllable access to food or shelter. In this description the terms “pet” and “animal” may be used interchangeably and generally refer to dogs and cats although other animals having similar features of size and shape may benefit.
2. Description of Prior Art
Many pets enjoy or need a certain amount of time outside the home for recreation or to answer nature's call, but most pet owners feed their animals inside the home to insure that other animals do not have access to the pet's food. In particular, foraging raccoons and opossums are becoming major problems in residential areas where they search for any available food source. Controlling access to the residence or to a feeding device is a desirable solution. In some situations there are pets that prefer to live outside and are fed on a routine by their owner, either inside or out, but at a time or in a manner that avoids conflict with stray pets and other animals. In such instances when the owner will be absent for several days, it is desirable for the pet to be able to “self control” its access to the food source. In prior art, the solution is to employ some means of proximate detection through magnets, transponders or transmitters carried or worn by the pet on a collar or harness. Such techniques present certain problems of complexity, expense, and possible pet discomfort that the present invention overcomes.
In U.S. Pat. No. 4,036,178 to Lee, et al., an electronic lock and key system is described in which a passive transponder in the form of a CMOS chip is worn on the pet or embedded subcutaneously. Such a technique is also used in pet identification systems and are known in the broader art as Radio Frequency Identification (RFID) systems. An advantage of such a system is that it can allow discrimination between several animals wearing uniquely encoded transponders. However such a system is relatively complex and expensive and somewhat restrictive due to limited range for sensing the transponder's responsive signal. In a pet access system this limited range dictates a restrictive aperture size for the portal or passageway through which the animal must pass to be close enough for sensing by the reader. A similar approach is found in U.S. Pat. No. 5,992,096 to De La Cerda, et al, which includes a motion detector that works in conjunction with an encoded pet tag. Using transponders for animal sensing is also a feature of U.S. Pat. No. 6,297,739 to Small and U.S. Pat. No. 6,349,671 to Lewis, et al., wherein the latter is for control of a feeding system. In U.S. Pat. No. 5,669,328 to Lanfranchi an active transmitter is worn on the pet's collar. This overcomes, somewhat, the sensing limitations of the previously cited patents but introduces the need for a battery to power the transmitter with the possibility of failure from battery depletion.
Other approaches include magnets worn on a collar such as described in U.S. Pat. No. 5,701,702 to Reid, et al., and in U.S. Pat. No. 6,453,847 to Brooks; and an ultrasonic transponder described in U.S. Pat. No. 5,872,516 to Bonge, Jr. In these the disadvantage of a bulky or heavy object attached to the collar is apparent and, in the case of Bong, Jr., the possibility of discomfort to the pet exists due to the ability of most pets to hear ultrasonic frequencies.
In the above referenced patents there are disclosures of various ways to effect the physical blocking or unblocking of passage or access to food through electrically or magnetically actuated locks, motor driven doors, etc. Although each has its own merit, it will be seen that an object of the present invention is that it be adaptable to any preferred electrically actuated access device.